Regensburg 2019 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 25: Granular Matter / Contact Dynamics
DY 25.3: Vortrag
Mittwoch, 3. April 2019, 10:15–10:30, H3
Non-equilibrium steady states, coexistence and criticality in driven quasi 2D granular matter — •Thomas Schindler and Sebastian C. Kapfer — Institut für Theoretische Physik I, Universität Erlangen-Nürnberg, Staudtstraße 7, 91058 Erlangen
Non-equilibrium steady states of vibrated inelastic frictionless spheres are in quasi-two-dimensional confinement via molecular dynamics simulations are presented. The phase diagram in the density-amplitude plane exhibits a fluid-like disordered and an ordered phase with threefold symmetry, as well as phase coexistence between the two. Moreover, there is a square bilayer state which is connected to the fluid by BKTHNY-type two-step melting with an intermediate tetratic phase.
The critical behavior of the two continuous transitions is studied in detail. For the fluid-tetratic transition critical exponents of γ= 1.73, η4 = 0.25, and z = 2.05 are obtained. The phase diagram topology is incompatible with any equilibrium free energy and features an anomalously diluted fluid in coexistence with the threefold cluster. A dynamical mechanism exists that brings about metastable traveling clusters and at the same time stable clusters with anisotropic shapes at low vibration amplitude.